title: PAK inactivation impairs social recognition in 3xTg-AD Mice without increasing brain deposition of tau and Aβ.
abstract: Defects in p21-activated kinase (PAK) are suspected to play a role in cognitive symptoms of Alzheimer's disease (AD). Dysfunction in PAK leads to cofilin activation, drebrin displacement from its actin-binding site, actin depolymerization/severing, and, ultimately, defects in spine dynamics and cognitive impairment in mice. To determine the role of PAK in AD, we first quantified PAK by immunoblotting in homogenates from the parietal neocortex of subjects with a clinical diagnosis of no cognitive impairment (n = 12), mild cognitive impairment (n = 12), or AD (n = 12). A loss of total PAK, detected in the cortex of AD patients (-39% versus controls), was correlated with cognitive impairment (r(2) = 0.148, p = 0.027) and deposition of total and phosphorylated tau (r(2) = 0.235 and r(2) = 0.206, respectively), but not with Aβ42 (r(2) = 0.056). Accordingly, we found a decrease of total PAK in the cortex of 12- and 20-month-old 3xTg-AD mice, an animal model of AD-like Aβ and tau neuropathologies. To determine whether PAK dysfunction aggravates AD phenotype, 3xTg-AD mice were crossed with dominant-negative PAK mice. PAK inactivation led to obliteration of social recognition in old 3xTg-AD mice, which was associated with a decrease in cortical drebrin (-25%), but without enhancement of Aβ/tau pathology or any clear electrophysiological signature. Overall, our data suggest that PAK decrease is a consequence of AD neuropathology and that therapeutic activation of PAK may exert symptomatic benefits on high brain function.
authors.affiliation: Faculté de pharmacie, Université Laval, Quebec City, G1V 0A6, Quebec, Canada.
authors.forename: Dany
authors.initials: D
authors.lastname: Arsenault
authors.forename: Alexandre
authors.initials: A
authors.lastname: Dal-Pan
authors.forename: Cyntia
authors.initials: C
authors.lastname: Tremblay
authors.forename: David A
authors.initials: DA
authors.lastname: Bennett
authors.forename: Matthieu J
authors.initials: MJ
authors.lastname: Guitton
authors.forename: Yves
authors.initials: Y
authors.lastname: De Koninck
authors.forename: Susumu
authors.initials: S
authors.lastname: Tonegawa
authors.forename: Frédéric
authors.initials: F
authors.lastname: Calon
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics* / Q000523:psychology*; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D001923:Brain Chemistry / Q000235:genetics; D003072:Cognition Disorders / Q000235:genetics / Q000523:psychology; D060825:Cognitive Dysfunction / Q000235:genetics / Q000523:psychology; D055724:Electrophysiological Phenomena; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D018408:Patch-Clamp Techniques; D021641:Recognition, Psychology / Q000502:physiology*; D012919:Social Behavior; D054462:p21-Activated Kinases / Q000502:physiology*; D016875:tau Proteins / Q000378:metabolism*
chemical_list: D016229:Amyloid beta-Peptides; D016875:tau Proteins; D054462:p21-Activated Kinases